1. Field of the Invention
Aspects of the present invention relate to a dummy cell for a battery pack and a mold for manufacturing the dummy cell.
2. Description of the Related Art
Unlike a primary battery a secondary battery is rechargeable. This has resulted in secondary batteries being used in a variety of electronic devices, such as mobile phones, PDAs, digital cameras, hybrid vehicles, and the like.
A secondary battery can be formed in various shapes, such as a cylindrical shape and a rectangular shape. A rectangular secondary battery is generally used for small electronic devices that require less power. A battery pack, in which a plurality of cylindrical secondary batteries are interconnected, is generally used in the devices requiring a lot of power.
As described above, a battery pack generally consists of a plurality of cylindrical secondary batteries, which are coupled in series (hereinafter, referred to as cylindrical cells). Each of the cylindrical cells includes a wound electrode assembly. The electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator disposed therebetween. The electrode assembly is housed in a cylindrical can, and a cap assembly is used to seal an opening of the can.
A battery pack includes an exterior case to house the cylindrical cells. A mounting process is executed, in which a plurality of cylindrical cells are electrically coupled to the exterior case. Further, the cylindrical cells can be mounted in mounting spaces of the exterior case, and according to the circumstances, some of the mounting spaces may remain empty. When an exterior case includes empty mounting spaces, the cylindrical cells may move, due to the vacant mounting space. Thus, a dummy cell is used to fill the vacant mounting space.
FIG. 1 is a perspective view illustrating a conventional dummy cell 1000, and FIG. 2 is a perspective view illustrating a mold for manufacturing the dummy cell 1000. As illustrated in FIG. 1, the conventional dummy cell 1000 is a hollow cylinder. Such a dummy cell 1000 is manufactured in a mold that includes a slide core 1400, as illustrated in FIG. 2.
Referring to FIGS. 2-3, a conventional mold includes an upper mold 1100; a lower mold 1200; slide cores 1400 that move reciprocally in a width direction of the mold; and pushing pins 1500 that move through the lower mold 1200.
The upper mold 1100 includes an injection valve 1120 and semicircular cavities 1130 that correspond to semicircular cavities 1220 of the lower mold 1200. The upper and lower molds 1100, 1200 include core grooves 1110 and 1210 and resin supply channels 1140, 1230.
The processes for manufacturing a conventional cylindrical dummy cell by using the metal mold will now be explained. The upper and lower molds 1100, 1200 are brought into contact with each other, such that the semicircular cavities 1130, 1220 are coupled together to form cylindrical cavities 1300. The slide cores 1400 are inserted into the core grooves 1110, 1210, such that cylindrical cores 1410 of the slide cores 1400 are inserted into the cylindrical cavities 1300.
A resin is injected into the injection valve 1120 and then flows through the resin supply channels 1140, 1230 and into the cylindrical cavities 1300. The resin is then hardened to form the dummy cells 1000.
The upper and lower metal molds 1100, 1200 and the slide cores 1400 are then separated. The dummy cells 1000 are ejected from the lower metal mold 1200, using the pushing pins 1500.
However, since the conventional dummy cell 1000 is tube-shaped, the amount of resin required for manufacturing the dummy cell 1000 is relatively large, thereby increasing costs. In addition, because the slide cores 1400 must be inserted and removed, the manufacturing process requires more time than would be otherwise required if the slide cores 1400 were not needed.